Re: [PATCH net v3] bonding: Fix unnecessary warnings and logs from bond_xdp_get_xmit_slave()

Nikolay Aleksandrov
2024-09-20T06:43:41Z

On 18/09/2024 17:06, Jiwon Kim wrote:
> syzbot reported a WARNING in bond_xdp_get_xmit_slave. To reproduce
> this[1], one bond device (bond1) has xdpdrv, which increases
> bpf_master_redirect_enabled_key. Another bond device (bond0) which is
> unsupported by XDP but its slave (veth3) has xdpgeneric that returns
> XDP_TX. This triggers WARN_ON_ONCE() from the xdp_master_redirect().
> To reduce unnecessary warnings and improve log management, we need to
> delete the WARN_ON_ONCE() and add ratelimit to the netdev_err().
>
> [1] Steps to reproduce:
> # Needs tx_xdp with return XDP_TX;
> ip l add veth0 type veth peer veth1
> ip l add veth3 type veth peer veth4
> ip l add bond0 type bond mode 6 # BOND_MODE_ALB, unsupported by XDP
> ip l add bond1 type bond # BOND_MODE_ROUNDROBIN by default
> ip l set veth0 master bond1
> ip l set bond1 up
> # Increases bpf_master_redirect_enabled_key
> ip l set dev bond1 xdpdrv object tx_xdp.o section xdp_tx
> ip l set veth3 master bond0
> ip l set bond0 up
> ip l set veth4 up
> # Triggers WARN_ON_ONCE() from the xdp_master_redirect()
> ip l set veth3 xdpgeneric object tx_xdp.o section xdp_tx
>
> Reported-by: syzbot+c187823a52ed505b2257@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=c187823a52ed505b2257
> Fixes: 9e2ee5c7e7c3 ("net, bonding: Add XDP support to the bonding driver")
> Signed-off-by: Jiwon Kim <jiwonaid0@gmail.com>
> ---
> v3: Fix subject and description
> v2: Change the patch to fix bond_xdp_get_xmit_slave
> ---
> drivers/net/bonding/bond_main.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index b560644ee1b1..b1bffd8e9a95 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -5610,9 +5610,9 @@ bond_xdp_get_xmit_slave(struct net_device *bond_dev, struct xdp_buff *xdp)
> break;
>
> default:
> - /* Should never happen. Mode guarded by bond_xdp_check() */
> - netdev_err(bond_dev, "Unknown bonding mode %d for xdp xmit\n", BOND_MODE(bond));
> - WARN_ON_ONCE(1);
> + if (net_ratelimit())
> + netdev_err(bond_dev, "Unknown bonding mode %d for xdp xmit\n",
> + BOND_MODE(bond));
> return NULL;
> }
>

Looks good to me, but next time wait 1 day before reposting another version.
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>